A Surgeon Image Credit: REUTERS

According to a report by The Center for Investigative Reporting (CIR), about 150 female prisoners were sterilised by the California Department of Corrections and Rehabilitation between the years 2006 and 2010 alone, without approval from the state.

Documents reveal that at least 148 women underwent tubal ligations during the five years alone while another 100 were made to agree for the procedure in the late 1990s.

Between 1997 and 2010, doctors were paid $147,460 (£98556.37) by the state for the procedure while inmates say that the medical staff forced them to undergo sterilisation. Those who were more likely to return to the prison in future were particularly targeted, the report says.

"I was like, 'Oh my God, that's not right. Do they think they're animals, and they don't want them to breed anymore?" 28-year-old Crystal Nguyen a former Valley State Prison inmate said.

Speaking of her own experience with the institution's OB-GYN, Dr. James Heinrich in 2006, Christina Cordero,34, said:

"As soon as he found out that I had five kids, he suggested that I look into getting it done. The closer I got to my due date, the more he talked about it. He made me feel like a bad mother if I didn't do it."

Cordero spent two years in prison for theft and was released in 2008.

"Today, I wish I would have never had it done," she said.

About five decades ago, forcing sterilisations on prisoners, the mentally ill and the poor was not very uncommon in California until it was officially banned by the state in 1979.

Sixty nine-year-old Heinrich, in an interview with CIR denied doing anything wrong and instead said that what he did was just help poor women. He also denied coercing anyone.

"Over a 10-year period, that isn't a huge amount of money," Heinrich said of the money spent by the state, "compared to what you save in welfare paying for these unwanted children - as they procreated more."

Daun Martin,73, a licensed psychologist pointed out that a lot of women, who are mostly on drugs and are pregnant, commit crimes so as to return to prison for better health care.

"Do I criticise those women for manipulating the system because they're pregnant? Absolutely not," Martin said. "But I don't think it should happen. And I'd like to find ways to decrease that," he added.

For the procedures, the state of California used state funds. However, sterilisations cannot be performed on inmates without approval from top medical officials in Sacramento. That too, permissions are required for every individual case since 1994.

Kimberly Jeffrey, 43, who resisted the procedure, was forced by a doctor while she was sedated and strapped to a surgical table for a C-section delivery in 2010.

"He said, 'So we're going to be doing this tubal ligation, right?' " Jeffrey said. "I'm like, 'Tubal ligation? What are you talking about? I don't want any procedure. I just want to have my baby.' I went into a straight panic."

State prison officials "are the real repeat offenders," Jeffrey who now lives in San Francisco with her 3-year-old son said. "They repeatedly offended me by denying me my right to dignity and humanity," she added.